As omnivores, piranhas will eat any food source available. As a result, Piranhas have a highly varied diet, consisting of everything from fruits and vegetables to other fish, and even human beings. A piranha's diet changes with age.
While they cannot eat as many different types of food as adults, the diet of young piranhas still consists of a wide range of foods. Newly hatched iranhas typically consume various fruits, plants and small crustaceans.
Adult piranhas hunt in groups called shoals that typically eat the fins and flesh of other fish. They tend to eat an animal alive and even will eat members of their shoals while attacking prey. Piranhas have been known to eat sick cattle that stick their heads in water to drink, young birds that fall from trees and even their own young.
A pet piranha's diet ideally mimics that of the piranhas' natural diet. In the wild, the diet typically consists of other large fish; frozen or processed fish provide the same nutrition. Occasionally, they will feed on a large carcase of an animal or on vegetables. Vegetables, therefore, are offered on occasion.